#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "MQTTClient.h"
#define ADDRESS "tcp://localhost:1883"
#define CLIENTID "ExampleClientSub"
#define TOPIC "MQTT Examples"
#define QOS 1
#define TIMEOUT 10000L

/**
 * @brief:异步mqtt客户端，subscribe示例
 * 
 * @brief:编译说明：
 * g++ main.cc 
 * -I /home/wsl/user/build/paho.mqtt/Eclipse-Paho-MQTT-C-1.3.8-Linux/include 
 * -L /home/wsl/user/build/paho.mqtt/Eclipse-Paho-MQTT-C-1.3.8-Linux/lib 
 * -lpaho-mqtt3c -lpthread
 * 
**/

volatile MQTTClient_deliveryToken deliveredtoken;
void delivered(void *context, MQTTClient_deliveryToken dt)
{
    printf("Message with token value %d delivery confirmed\n", dt);
    deliveredtoken = dt;
}
int msgarrvd(void *context, char *topicName, int topicLen, MQTTClient_message *message)
{
    int i;
    char *payloadptr;
    printf("Message arrived\n");
    printf("     topic: %s\n", topicName);
    printf("   message: ");
    payloadptr = (char *)message->payload;
    for (i = 0; i < message->payloadlen; i++)
    {
        putchar(*payloadptr++);
    }
    putchar('\n');
    MQTTClient_freeMessage(&message);
    MQTTClient_free(topicName);
    return 1;
}
void connlost(void *context, char *cause)
{
    printf("\nConnection lost\n");
    printf("     cause: %s\n", cause);
}
int main(int argc, char *argv[])
{
    MQTTClient client;
    MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
    int rc;
    int ch;
    MQTTClient_create(&client, ADDRESS, CLIENTID,
                      MQTTCLIENT_PERSISTENCE_NONE, NULL);
    conn_opts.keepAliveInterval = 20;
    conn_opts.cleansession = 1;
    MQTTClient_setCallbacks(client, NULL, connlost, msgarrvd, delivered);
    if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)
    {
        printf("Failed to connect, return code %d\n", rc);
        exit(EXIT_FAILURE);
    }
    printf("Subscribing to topic %s\nfor client %s using QoS%d\n\n"
           "Press Q<Enter> to quit\n\n",
           TOPIC, CLIENTID, QOS);
    MQTTClient_subscribe(client, TOPIC, QOS);
    do
    {
        ch = getchar();
    } while (ch != 'Q' && ch != 'q');
    MQTTClient_disconnect(client, 10000);
    MQTTClient_destroy(&client);
    return rc;
}